Computer Science Programming Basics in Ruby

7.4 Summary

We discussed the various sorting schemes, both comparison-based and non-comparison-based, and the strengths of each. We introduced the field of complexity analysis, a tool used to quantify the performance of an algorithm. Finally, we discussed searching and provided a real-world example of searching techniques.

Specifically, we described four elementary sorting algorithms. The first three presented—selection, insertion, and bubble sort—are comparison based. That is, elements are compared against one another to determine a sorted ordering. The fourth algorithm, radix sort, differs substantially. Instead of comparing elements, radix sort orders the elements according to their representation, starting from the rightmost digit. Once all digits of the element representation are processed, the list is sorted. The complexity of these sorting algorithms is presented in Table 7-1, where n represents the number of elements in the list and k represents the number of digits needed to represent the largest element. The best-case scenario occurs when the original list is already sorted; the worst-case scenario occurs when the original list is in reserve order; and the average-case scenario represents an original random ordering.

Table 7-1. Sort algorithm complexity summary

	Best case	Worst case	Average case
Selection sort
Insertion sort
Bubble sort
Radix sort

Likewise, ...